If you’ve got an Aluminium Powerbook, (either the last of the G4 models or the new intel mac pro models) they are a great machine (the 15 inch is my favourite) but after a few years the hinge can get loose. Thankfully this is not like the old Titanium powerbooks where the hinge was broken, it is just a matter of a few screws that need to be tightened! Here’s how to do it.
1. First of course is power it down and remove the battery. Then you need to find two screws like this, one each side, and undo them with a torx size 6 screwdriver.
2. Now carefully prise the back of the lid apart like this. Be VERY CAREFULL when prising the back off the screen not to damage the plastic, or apply too much pressure, or force anything. There are little lugs, and you need to prise the plastic over those lugs and back to get it off. The plastic comes off the back with the case that has the apple logo on it, so you pry between the plastic and the aluminium surrounding the LCD screen like this.

When you have worked your way up the sites, and over the top, the lid will pretty much fall off like this.
These are the screws you need to tighten, there are 4, and the ones on the left are covered by a little piece of yellow sticky tape you need to remove and then replace after you are finished.

The tightening!

That’s it, now carefully put the sticky tape and lid back together, and replace the two screws. It should take about 1/2 hr to an hour.